1-phenyl-3, 3-dimethylspiro[(2&#39;h-1&#39;-benzopyran)-2&#39;, 2&#39;-indoline] compound



United States Patent 3,231,584 l-PHENYL-S,S-DIMETHYLSPIROKZ'H-1-BENZO- PYRAN)-2,2'-INDOLINE] COMPOUND Elliot Berman, East Braintree, Mass, and John E. G.

Taylor, Dayton, Ohio, assignors to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland No Drawing. Filed May 1, 1962, Ser. No. 191,431

1 Claim. (Cl. 260--319) This invention relates to the 1-phenyl-3,3-dimethylspiro (2H-l'-benzopyran) 2,2 -indoline] compound of the formula:

wherein R is one or more independently selected radicals, to be specified hereinafter, at one or more of the 5', 6, 7, and 8' positions.

This application is a continuation-in-part of copending United States patent application Serial No. 827,462, filed July 16, 1959, in the names of Elliott Berman and John E. G. Taylor, now abandoned.

These compounds in solution are substantially colorless but may be changed, at will, to a colored state, in which the 2' 1 bond is broken, by irradiating such with light predominating in components from blue through ultraviolet wave-lengths, and reversed back, at will, in solution in substantially colorless state, by subjecting such solution to light predominating in components of wave-lengths longer than blue up through the infra-red.

These compounds are useful in sensitizing record material so as to exhibit data by colored and uncolored areas thereon, which data has been selectively recorded thereon, or erased therefrom, by the application of recording light or erasing light or heat.

Solutions of the compounds are also useful as components of optical filters which darken on being subjected to ultra-violet or blue light, such filters being adapted for protecting the eyes from tissue-damaging light or from temporarily-induced blindness from excessive light, inasmuch as they respond immediately to the coloring light waves which accompany great excesses of visible light.

Reference is made to an application of applicant Elliott Berman for United States Letters Patent, "Serial No. 827,420, filed July 14, 1959, for details of how the novel derivative compounds of this application may be incorporated in an eye-protecting filter. Reference also is made. to applicant Elliot Bermans application for United States Letters Patent, Serial No. 654,578, filed April 23, 1957, which issued into United States Patent No. 2,953,454 on September 20, 1960, relative to the use of such compounds in a record sheet on which data may be selectively recorded by light, and erased therefrom by light.

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These compounds vary in their stability, due to thermal activity, the unsubstituted compound being reversibly colorable and stable in solution in the colored state only at low temperature-say about minus 60 degrees centigrade or belowin the absence of change-provoking light, whereas those derivatives having the substituents or radicals hereinafter disclosed in any of the 5, 6', 7 and 8' positions, which tend to weaken the spiro-carbon-to-oxygen 2'1' bond, and are reversibly colorable, are characterized by having low thermal stability when in the colored form -(-short-half-life compounds) at higher temperatures, such as at room temperatures and above, but within the range of normal human activity temperatures.

It should be understood that the novel compounds of this invention will, in the absence of exposure to shortwave-length change-provoking light, remain in the colorless state indefinitely, when in solution, either at or about normal room temperatures; and that said compounds when in the colored state, in solution, not only will quickly revert to the colorless form by the action of longer-wavelength change-provoking light, but will also, even in the dark, rapidly revert to said colorless state, by thermal activity, at or about normal room temperatures. The rate of reversion is temperature-dependent, the rate increasing with increasing temperature. The rate at which these compounds revert from the colored form to the colorless form is normally expressed as the half-life of the colored form of the compound and is a quantitative measure of the thermal stability of such compounds at or about room temperature. It has been found that, when properly modified, various classes of compounds, particularly spiropyran compounds, may be made in which the room temperature thermal stability of the colored form varies from a half-life of a fraction of a second to a half-life of several months. The thermal stability of the novel compounds of this invention falls in the category of shorthalf-life compounds, said half-life varying from about a few minutes to less than a second.

A suitable method for determining the half-life of the colored form of the instant compound is to determine, at a selected wave-length, the rate of decrease in absorbence of a solution of the compound while kept in the dark, over a known time interval, and, by use of the Well-known rate formulas and a graph plot of the variables, to calculate the interval of time required for the absorben'ce to decrease from a maximum value to half this value.

By the term solution, as used herein, is meant the homogeneous mixture of one of more of the claimed compounds with a solid or liquid substance.

Among the many possible radicals or substituents which may be attached at any one of the 5, 6', 7', and 8 positions are the following: CH CH H CH(CH C(CH the phenyl group C H CF CN; COCH I0 CH CH=CH and CO CH Any of the above radicals or substituents or group of sterically compatible substituents or radicals may be selected. for attachment at said positions, and such compounds may be prepared by condensing the selectively substituted salicylaldehyde (to give substituents in the 5, 6, 7', and 8' positions, as desired) with 1-phenyl-3,3- dimethyl-2-methyleneindoline.

As is evident from the foregoing a large number of lphenyl compounds of the type disclosed are within the scope of the invention; however, the preferred compounds are defined as compounds having the following structural formula:

wherein R is a member selected from the group consisting of-NO and -OCH in the 6 and 8' positions, respectively; NO;,, in the 6' position; and NO in the 6 and 8' positions.

Even though the intermediate 1-phenyl-3,3-dimethyl Z-methyleneindoline apparently is not a novel compond, the method of preparing it will be described, inasmuch as no method for its preparation appears to have been published.

In preparing 1phenyl-B,3dimethyl-2-methyleneindoline, the first step consists of forming the hydrochloride salt of N,N-diphenylhydrazine as follows:

A 198-gram (1.0 mole) sample of N-nitroso diphenylamine was added to 1250 ml. of 95% ethanol in a 3-liter flask, and to this mixture was added 233 grams (3.5 moles) of zinc duct. The reaction mixture was cooled to below 10 degrees centigrade and maintained below that temperature during the addition of 240 ml. of glacial acetic acid. Addition of the acid took about 1% hours. After the addition of the acid, the reaction mixture was filtered, and the filtrate obtained was reduced to one fourth of its volume by evaporation on a steam bath and then diluted with its own volume of water. The resulting solution was treated with about 400 m1. of concentrated hydrochloric acid, and the salt formed was collected on a filter. The salt of the N,N-diphenyl hydrazine present was separated from the by-products by partially dissolving the collected precipitate in warm very dilute hydrochloric acid and removing the undissolved by-products byfiltration. The filtrate was treated with concentrated hydrochloric acid, and the salt of the hydrazine (101 grams, which is 0.45 mole), which precipitated, was removed by filtration, giving the hydrochloride salt of N,N-di phenylhydrazine, which has the structure The thus-made hydrochloride salt of N,N-diphenylhydrazine is condensed with methyl isopropyl ketone to form the N,N-diphenylhydrazone of methyl isopropyl ketone, which in turn is made to undergo ring closure to 1-phenyl-3,3dimethyl-Zmethyleneindoline as follows:

A dried 26.5-gram (0.12 mole) amount of N,N-diphenylhydrazine hydrochloride is mixed with 11 grams (0.12 mole) of methyl isopropyl ketone in 100 ml. of absolute ethanol, and the mixture is refluxed for 1% hours with a drying tube attached to the condenser to exclude entry of Water vapor. The solution then is cooled and filtered to remove any precipitated salts. To a flask containing the filtrate, which contains the just-prepared N,N- diphenylhydrazone' of methyl isopropyl ketone, is added 110 grams of zinc chloride. The reaction mixture is protected from water vapor by a drying tube fixed to the neck of the flask and is stirred for 1% hours. The reaction mixture is made strongly basic with a concentrated aqueous solution of potassium hydroxide and then extracted with ethyl ether. The ether extract is dried and vacuum-distilled under a nitrogen atmosphere. The fraction which distills at 100102/0.01 mm. is collected as the desired 1-phenyl-3,3dimethyl-Z-methyleneindoline, which has the structure:

In general, the novel compounds of the invention having selected radicals or substituents at the 5' 6, 7', and 8' positions are synthesized by condensing the intermediate lphenyl-3,3-dimethyl2-methyleneindoline with a substituted salicylaldehyde in which the substituents or radicals are so selected and located as to provide a condensation product having the desired radicals at one or more of the said 5', 6, 7, and 8 positions.

Example I In this example will be described the preparation of the 6nitr o-8'-methoxy derivative, having the structure A 2.0-fram (0.0085 mole) amount of 1-phenyl-3,3-dimethyl-2methyleneindoline and 1.67 grams (0.0085 mole) of 3methoxy-5-nitrosalicylaldehyde are dissolved in 20 ml. of ethanol, and the resulting solution is refluxed for two hours. The reaction contents is cooled and filtered to give 2.4 grams of the desired product, which on recrystallization from alcohol melts at 179.5 to 181 degrees centigrade.

Example II In this example will be described the preparation of the 6'-nitro derivative, having the structure 5 This is prepared by the same method as the compound of Example I, except that S-nitrosalicylaldehyde is used instead of 3-methoxy-S-nitrosalicylaldehyde, in equimolar amounts.

Example III In this example, the preparation of the 6',8'-dinitro derivative will be described. This is prepared by the same method as the compound of Example II, except that 3,5- dinitrosalicylaldehyde is used instead of 3-methoxy-5- nitrosalicylaldehyde, in equimolar amounts. This compound has the structure Other substituted salicylaldehydes, having substituents or radicals selected from the previously given list of substituents, may be used to make numerous other l-phenyl compounds of the type within the scope of this invention by following the methods of preparation disclosed hereinabove;

6 What is claimed is: The compound of the formula:

H 36 C H 3 References Cited by the Examiner UNITED STATES PATENTS 2,338,782 -1/ 1944 Riester 260-240 2,953,454 9/1960 Berman 260-319 3,085,469 4/1963 Carlson 88-24 3,100,778 8-1963 Berman 260-319 OTHER REFERENCES Hirshberg et al.: J. Chem. Society (London), pp. 3129- 3136 (1954).

Knott: J. Chem. Soc. (London), pp. 3038-3047 (1951).

Koelsch et al.: I. Am. Chem. Soc., vol. 74, pp. 6288-- 6289 (1952).

Wizinger et al.: Helv. Chimica Acta, volume 23, pp. 247-271 (1940).

NICHOLAS S. RIZZO, Primary Examiner.

IRVING MARCUS, Examiner. 

